Method for the aluminothermic preparation of air quenching steel



Patented Apr. 17, 1934- METHOD FOR THE ALUMINOTHERMIC PREPARATION or AIR QUENCHING STEEL Clarence Leon Delachaux, Gennevilliers, France lo Drawing. Application January 22, 1932, Serial No. 588,242. In France January 6, 1930 i 5 Claims. ('01. '15- 45) My invention is a continuation in part of my cppending application Ser. No. 460,100.

My invention has for its object improvements in or relating to the aluminothermic self-hardening preparation of a self hardening steel adapted for welding purposes and containing beyond the usual components of mild steel, components such as nickel, chromium, moldybdenum, tungsten and if required titanium, vanadium, boron and copper. I

. It is known that in the case of the usual alumino-thermic method of preparing steel, where the reaction Al+Fe3O4 is executed at a high temperature about 2500 C. and ends very speedily, soft steel scrap is generally added to the .aluminothermic mixture, said scrap serving to cool the reaction and being melted in its turn by the heat evolved by the alumino-thermic reaction.

For obtaining certain alloy steels containing silicon and manganese, it has been already proposed to add instead of steel scrap analloy containing manganese and silicon, said alloy being constituted for instance by grains."

This addition hasa double part to play. On one hand the manganese and the silicon thu's added act as deoxidizing or reducing agents. On the other hand part of this manganese and silicon remains in the final steel obtained.

In the case of my invention no manganese or silicon additions are provided with a view to increasing the contents'of manganese or silicon in the final product, -i. e. in the steel having the coniposition defined in the opening paragraph of'the specification.

According to my invention and with .a view to obtaining in a'reliable 'and uniform manner good and homogeneous steel of the composition given hereinabove, I distinguish those additio'ns'which are to remain in the steel obtained and which I add to the aluminothermic mixture, from the deoxidizing or reducing. agents which are not in-' tended to remain in the steel obtained and which I add once the alumino'thermic reaction, i. e. the reaction of Fe3O4 with Al, has begun. These deoxidizing agents may consist of iron alloys having high contents ofdeoxidizing elements (morethan 75 of Mn or Si) or of compound silicides ing reaction Al+FeaO4. As to the additions which are to remain in the final steel and which are added at the beginning of the process to the aluininothermic mixture, they may according, to my invention be incorporated under two forms. The part corresponding to the first form may be added after it has been diluted or alloyed in a metalisteel or alloy) under the form of shavings or grains or the like more or less finely divided parts the percentage of which may reach upto about 40% of the weight ofythe aluminothermicmixture -(aluminium+iron oxide). But the totality ofthe additions cannot generally be incorporated in this manner as they would excessively cool the aluminothermic reaction.

I am also sometimes lead to' retain a certain proportion of soft steel scraps as in the ordinary aluminothermic method having reduced contents, say less than 70% of the elements chromium molybdenum, tungsteri. I may use also compound iron alloys contain-- ing, the desired elements combined two by two, three by three etc. I avoid moreover adding to these alloys elements such as manganese, silicon etc. which would have to be eliminated as slags after they haveacted. Example v Supposing a selfhardening weld steelis to be prepared, having the following composition:

0,8 to 1,2% or more- Mn= 0,3 to about 0,6 %Si=about 0 ,5% or less- Mo=about 0,075% or more-P=as little as pos- -'sible- S= as little as'possible--Ti=about 0,1% or less.

I will proceed as follows: (a) .I add to the aluminothermic mixture having substantially the theoretical proportions viz: 233%, A1+'l6,3% F6304, firstly 10 to about 20% in weight of a mixture of shavingsof a steel i The remainder of the additions may be added C about 2 to 4% Ni about 15 to,25%

Cr about 5 to 10% Mo about 0,5% or less Ti about 0,5% or less Si about 0,5% or less Mn about 0,4% or less P and S as littleas possible.

The amounts of Mn and Si should be adjusted.

in accordance with the remaining contents subsequently provided by the deoxidizing agents a small portion of the Mn and Si of which passes into the final steel.

Secondly I add the complement required for giving the final steel the desired contents, these contents being added under the form of cast iron grains containing about 2 to 4% of C (for the carbon) of ferro-chromium, nickel or ferronickel, ferro-carbon-nickel, ferro-nickel-chromium, ferro-carbon-nickel-chromium etc. or ox: ides of chromium or nickel (for the carbon, chromium and nickel) term-molybdenum (for the molybdenum), iron etc. (b) Finally as soon as the aluminothermic re action which is very short (5 to 30 seconds) has begun I add small amounts of deoxidizing agents constituted by term-manganese having high contents of manganese, ferro-silicon having high contents of silicon or ferro-silico-aluniinium e c.

This example, of course, is given merely as an indication; other examples could be considered without changing the principle or the invention.

What I claim is:

1. A method for the aluminothermic preparation of a cast self-hardening steel consisting in incorporating in the aluminothermic mixture of aluminium and iron oxide about 10 to 40% of an alloy in a finely divided state containing elements, selected from a group consisting of C, Cr, Ni, Mo, W, .Ti, 30, Va, Cu, which are to remain in the final steel and in adding only when the aluminothermic reaction has begun, substances having high contents of material acting as deoxidizing agents and selected from a group consisting of manganese, silicon, aluminium, boron, vanadium and titanium.

2. A method for the aluminothermic preparation of a cast self-hardening steel consisting in incorporating in the aluminothermic mixture of aluminium and iron oxide about 10 to 40% an alloy in a finely divided state containing elements, selected from a group consisting of C, Cr,

Ni, Mo, W, Ti, 130, Va, Cu, which are to remain in the final steel together with a complementary amount of metallic nickel and in adding only when the aluminothermic reaction has begun, substances having high contents of material acting as deoxidizing agents and selected from a group consisting of manganese, silicon, aluminium, boron, vanadium and titanium.

3. A method for the aluminothermic preparation of a cast self-hardening steel consisting in incorporating in the aluminothermic mixture of aluminium and iron oxide about 10 to 40% 01' an alloy in'a finely divided state containing elements, selected from a group consisting of C, Cr, Ni, Mo, W, Ti, Bo, Va, Cu, which are to remain in the final steel together with a complementary amount of oxides of elements selected from a group consisting of Ni, Cr, Mo, W, Cu, Va, Ti, Bo and in adding only when the aluminothermic reaction has begun, substances having high contents of material acting as deoxidizing agents and selected from a group consisting oi manganese, silicon, aluminium, boron, vanadium and titanium. r

4'. A method forthe aluminothermic preparation of a cast self-hardening steel consisting in incorporating in the aluminothermic mixture of aluminium and iron oxide about 10 to 40% of an alloy in a finely divided state containing elements, selected from a group consisting of C, Cr, Ni, Mo, W, Ti, Bo, Va, Cu, which are to remain in the final steel, the contents of which elements is the highest consistent with a good production of this alloy, together with a complemental alloy containing up to about 4% of carbon and certain elements selected from the above disclosed group,

the contenPsof at least one of said elements being higher than in the preceding alloy without being h gher than 70% and in adding only when the aluminothermic reaction has begun, substances having high contents of material acting as deoxidizing agents and selected from a group aluminothermic reaction has begun, substances havinghigh contents of material acting as deoxidizingagents and selected from a group consisting of manganese, silicon,v aluminium, boron, vanadium and titanium.

CLARENCE LEON DELACHAUX. 

